Refrigeration control system



Zinnentqr (Ittomeg M MW my a mm E E 2 WW2 mm mw c N A @N E w m m 8 JQE ROBB Filed April 30, 1938 REFRIGERATION CONTROL SYSTEM TGIDWIEIR cammumir Nov. 26, 1940.

Patented Nov. 26, 1940 REFRIGERATION CONTROL SYSTEM Joseph E. Robb, Overland Park, Kans., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application April 30, 1938, Serial No. 205,290

17 Claims.

This invention relates to refrigeration systems and is more particularly concerned with automatic controls therefor.

In refrigeration systems for providing refrigeration for air conditioning large buildings, ithas been common to locate the heavy machinery such as compressors, pumps, and condensers in the basement of the building while locating the cooling towers on the roof of the building. In large systems it has also been customary to utilize a number of compressors and to vary the number of compressors in operation in accordance with the load. It has also been customary to utilize a plurality of cooling towers and to vary the number of cooling towers in operation in accordance with the load on the system. Heretofore where a plurality of cooling towers have been employed, it has been necessary to provide separate 2o cooling tower pumps and conduits leading from the condenser to each cooling tower, in order to provide for independent operation of the cooling towers. The conduits between the cooling tower pumps and the cooling towers must necessarily be of relatively large diameter and must extend the entire height of the building. These long runs of large size pipes are quite expensive. It is an object of my invention to reduce the cost of installations utilizing a plurality of cooling towers by providing an arrangement by which the cooling towers may be served by a single supply conduit while at the same time providing for independent operation of the cooling towers.

It is a further object of my invention to pro- 35 vide a suitable control system for refrigeration systems which automatically varies the number of compressors and the number of cooling towers in operation in accordance with the load on the refrigeration system. 40 It is a further object of this invention to provide a control system for refrigeration systems which automatically places the cooling tower pump, the cooling tower fan, and compressor into operation and which prevents the compressor from operating unless both the cooling tower pump and fan are operating. Still another object of this invention is to provide an automatic control system which acts to check the operation of the various pumps and fans and which prevents operation of a compressor in the event that the remainder of the refrigeration system is not operating properly.

A still further object of this invention is the provision of a control system of this type which not only checks the operation of the various pumps and fans, but whichalso places these instrumentalities into operation in sequence to thereby avoid overloading of the power supply due to simultaneous starting of a plurality of motors.

Other objects consist of various combinations and subcombinations of control apparatus and will become apparent from the following description and the appended claims.

For a full disclosure of my invention, reference is made to the following detailed description and to-the accompanying drawing, the single figure of which illustrates diagrammatically a refrigeration control system embodying the features of my invention.

' Referring to the drawing, reference character I indicates an air conditioning chamber which may be provided with an inlet or return duct 2 which leads from a space to be conditioned, and a fresh air duct 3. The outlet of this chamber may be connected to a fan 4 which discharges the air through a suitable discharge duct to the space being conditioned. The fan 4 may be driven by means of a motor 5. Located within the condition chamber is a cooling coil 6 which may be connected by a pipe 1 to the discharge of a pump 8. The inlet of this pump 8 may be connected by pipes 9 and Hi to a water cooler II. The pump 8 may be driven by means of an electric motor l2 under the control of a manual switch l3. The water cooler ll may be an indirect heat exchanger for passing the water to be cooled into heat exchange relationship with evaporating refrigerant for thereby cooling the water. When the switch I3 is closed for placing the pump 8 into operation, Water will be withdrawn from the water cooler ll through pipe in and discharged through the pipe I to the cooling coil 6, this water then flowing through an outlet pipe l4 and check valve I5 to a pipe l6 which leads to the inlet of the water cooler H. The pump 8 therefore acts to circulate Water between the cooling coil 6 and the water cooler ll.

Attached to the discharge pipe I of the pump 8 is a pressure responsive device generally indicated at IT. This pressure controller may consist of a bellows l8 which is connected by a tube I9 to the pipe 1. The bellows I8 may actuate a pivoted mercury switch carrier 2Ucarrying a mercury switch 2|. The bellows l8 may be loaded by means of a spring 22 for causing the bellows to collapse thereby tilting the mercury switch to open position as shownwhen the pressure in pipe I is'at a value indicating that the pump 8 is not 15 coil ditioning the air of another or auxiliary space.

This conditioning chamber is shown as being connected to a fan 26 which is driven by means of a fan motor 21. Within the conditioning chamber 25 is a cooling coil 28, the inlet of this cooling being connected by pipe 29 to a circulating pump 38. The'inlet of circulating pump 38 is connected by a pipe 3| to a valve 32, this valve being in turn connected to the pipe I8 which leads from the outlet of the water cooler I The 20 outlet of the cooling coil 28 is connected by a pipe 33 through a check valve 34 to the pipe I 8 leading to the inlet of the water cooler I I. Thus when the valve 32 is opened and the pump 38 is in operation the pump 38 will circulate water from 25 the outlet of the water cooler through the cooling coil 28 back to the water cooler. The valve 32 may be actuated by means of a valve motor 35. This valve motor 35 may be of any suitable type and is herein shown as comprising a 180 movement type for either opening the valve 32 wide or closing this valve. This motor in addition to actuating the valve 32 may also actuate an auxiliary switch 38, this switch being indicated diagrammatically as comprising a pivoted switch carrier 31 actuated by the valve stem of valve 32. This switch carrier carries a mercury switch 38 which controls the starting box 39 for themotor 48 which drives the pump 38. When the valve 32 is closed,the mercury switch 38 is tilted to open position for causing the starting box 39 to place the pump motor 48 out of operation. When the motor 35 operates to open the valve 32, however, the switch 38 will be tilted to closed position for thereby causing the starting box 39 to place the pump motor 48 into operation. The valve motor 35 utilizes a three-wire control circuit and is controlled by means of a relay 4| which may consist of a relay coil 42 which actuates through a suitable armature (not shown), a switch arm 43 which cooperates with contacts 44 and 45. The switch arm 43 is connected by a wire 48 to the common motor control terminal while the con- .tacts 44 and 45 are connected to the other two motor control terminals by wires 41 and 48. When the switch arm 43 engages contact 45 the motor 48 will assume a position for closing the valve 32 as shown. When the switch arm 43 engages contact however, the motor will run to a position for opening the valve 32. The relay coil 42 is connected by wires 49 and 58 across one phase of the power circuit for the fan motor 21. Thus when the fan motor 21 is energized by closing the switch 5|, the relay coil 42 will be energized which will cause the switch arm 43 to engage contact 44 thereby causing the valve motor '35 to open the valve, and to close mercury switch 38 for placing the pump motor 48 into operation. When the motor .21 is deenergized however as by opening the switch 5|, the switch arm 43 of relay 4| will engage contact 45 thus causing the valve motor 35 to close the valve 32 and to open mercury switch 38 for placing the pump motor 48 out of operation. .The auxiliary air conditioner may therefore be readily placed into or out of operain operation. When the pump 8 is'started, howtion simply by actuating the switch 5| in the fan motor circuit.

Referring to the refrigerant circuit for the water cooler, reference characters 55, 56, 51, and 58 indicate refrigerant compressors which may be driven by electric motors 59, 68, 8|, and 82, respectively, these motors in turn being provided with starting boxes 83, 84, 85, and 86. The discharge of each compressor is connected to a high pressure header 8! which in turn is connected to the refrigerant inlet of a condenser-receiver 88. It will be understood that the compressed refrigerant will be condensed in the condenserreceiver, the thereby liquifled refrigerant passing through a liquid line 89 and expansion valve 18 into the water cooler I wherein it evaporates for cooling the water passing through the water cooler. water cooler through a suction line H which is connected to the inlets of the compressors 5 5, 58, 51, and 58, as shown.

In order to provide a source of cooled water for condensing the refrigerant in the condenser receiver 88, a pair of cooling towers I2 and I3 are provided. These cooling towers may be of any desired type and are diagrammatically illustrated as beingprovided with spray pipes I4 and I5 and with sumps I8 and IT. The cooling tower I2 is provided with a fan I8 which may be driven by an electric motor I9 under the control of a starting box 88. The cooling tower 13 may be provided with a similar fan 8| driven by an electric motor 82 under the control of a starting box 83. The sumps 18 and 11 of the cooling towers are connected by pipes 84 and 85 to the cooling water inlet of the condenser-receiver 88 for thereby delivering cooled water to this condenser-receiver.

The cooling water outlet of the condenserreceiver is connected by pipes 88 and 81 to cooling tower pumps 88 and 89, respectively. The pump 88 may be driven by means of an electric motor 98 controlled by a starting box or relay 9|. This starting box is indicated as comprising a starter coil 92 which actuates through a suitable armature, the switch arms 93 which are interposed in the three-phase power supply line for the motor 98. When the coil 92 is energized, the switch arms 93 will be brought into engagement with their respective contacts for completing the power circuit to the motor 98 for placing the pump 88 into operation, When the coil 92 is deenergized however, the switch arms 93 will disengage their contacts for interrupting the power circuit to the motor 98. The pump 89 may be driven by an electric motor 94 which is controlled by a starting box 95 which may be similar to the starting box 9| for motor 98.

The discharge of the pump 88may be connected by a pipe 98 and check valve 98a to a header 91, and the discharge of the pump 89 may be connected. by pipe 98 and check valve 99 to this header. Th header 9'! in-turn is connected by a pipe I88 which leads upwardly through the building to the cooling towers I2 and 13 which may be located on the roof of the building. The pipe I88 is shown asbeing connected by pipe |8I to the spray pipe 14 of the cooling tower I2. This pipe I88 is also connected through a valve I82 and the pipe I82a to the spray pipe of the cooling tower I3. 'I'he valve I82 is actuated by means of a two-position type of valve motor i853.

This valve motor may be similar to the valve motor 35 and may be controlled by means of a relay I84. This relay may consist of a relay coil The evaporated refrigerant leaves the I05 which actuates through a suitable armature, a switch arm I06 cooperating with contacts I01 and I08. When the relay coil I05 is deenergized, the switch arm I06 will engage the contact I08 as shown and this will cause the valve motor I03 to close the valve I02. When the relay coil I05 is energized, the switch arm I06 will engage contact I01 which will cause the valve motor I03 to open the valve I02. The valve motor also actuates an auxiliary switch I09 shown as consisting of a mercury switch 0, this switch is arranged to be open whenever the valve I02 is closed, while being closed whenever the valve I02 is open. The purpose of auxiliary switch I09 will become apparent as this description proceeds. Reference character II5 indicates a pressur responsive device which is responsive to the pressure in pipe 96. This control may be similar to the pressure controller I1 and includes a bellows II6 connected by pipe II1 to the pipe 96. This bellows actuates a mercury switch NB. This instrument may be so designed and adjusted that the bellows I I6 collapses sufficiently to tilt switch I I8 to open position when the pressure in pipe 96 is so low as to indicate that pump 88 is not in operation. When the pump 88 is in operation, the resulting increasein pressure in pipe 96 will cause the bellows II8 to expand for tilting the mercury switch I I8 to closed position.

Reference character I20 indicates a pressure responsive device for checking the operation of the pump 89 and may be exactly the same as the controller II5. This controller is shown as comprising a bellows I2I connected by a tube I22 to the discharge pipe 98 of pump 89. When the pump 89 is not in operation the mercury switch I23 of the controller I20 will be opened, while when the pump 89 is in operation, this mercury switch will be tilted to closed position.

Reference character I25 indicates a sail switch y g'hich responds to the action of the cooling tower fan 8|. This sail switch may be of any desired type and is diagrammatically illustrated as comprising a pivoted vane I26 is located in the discharge of the fan 8|. This vaneactuates a mercury switch I21. When the fan 8| is not in operation the vane I26 will assume the position shown in which the mercury switch I21 is tilted to open position. However, when the fan 8| is in operation, the vane I26 will swing in a clockwise direction due to the impact of the moving air, this tilting the mercury switch' I21 to closed position. The cooling tower fan 18 is provided with a similar sail switch including a mercury switch I28 which opens when the fan 18 is not in operation but which closes when this fan is placed into operation.

Reference character I30 indicates a potentiometer type of thermostat. This thermostat is shown as comprising a bellows |3I which is connected by a capillary tube I32 to a control bulb I33 which is located upon the pipe I0 leading from the water cooler. The bulb I33, tube I32, and bellows I3I are charged with a suitable volatile fill for causing the pressure within bellows |3| to vary with changes in temperature of the water passing through pipe I0. The bellows I3I may actuate a bell crank lever having an actuating arm I35 and a control arm or slider I35 which cooperates with a control resistance I36 to form a potentiometer controller. As the temperature of the cold water passing to the cooling coils 6 or 28 decreases, the pressure within bellows I3I will decrease, this causing the control arm or slider I35 to travel to the right across control resistance I36 under the action of a. spring I31. As the water temperature increases, however, the bellows I3I will expand for causing movement of the slider H5 in the opposite direction. v The thermostat I30 controls a step controller generally indicated as I38. This step controller includes a proportioning motor I39 which may be of the type shown and described in Patent 2,028,110 issued to Daniel G. Taylor 'on January 14, 1936. This type of motor is provided with an operating shaft I40 and is adapted to position this operating shaft under the control of a potentiometer type of controller, and provides a definite angular position of its operating shaft for each position of the slider I35 on the control resistance I36. The operating shaft I40 may actuate a series of cams I4I, I42, I43,and I44 which in turn actuate a series of mercury switches I45, I46, I41, and I48. It will be noted that the cams are mounted upon the shaft I40 in a manner to provide for sequential actuation of the mercury switches I45, I46, I41 and I48 in the order named. When the temperature of the cooling water is relatively low, the slider I35 will engage the extreme right-hand end of resistance I36, this causing the motor to assume its extreme counterclockwise limit of rotation wherein the mercury switches I45, I48, I41, and I48 are opened. As the temperature of the cooled water increases, the slider I35 will move to the left on resistance I38, this causing the proportioning motor I39 to rotate its shaft in a clockwise direction. At first the mercury switch I45 will be closed. Upon further increase in temperature, the mercury switch I46 will be closed, and upon still further temperature increase the switches I41 and I48 will be sequentially closed.

Operation pump motor I2 for the cold water circulating pump 8 is out of operation as indicated by the switch I3 being open. Also the cold water temperature is relatively low as indicated by the slider I35 being positioned upon resistance I36 at a point near its right-hand end. For this position of the slider, the step controller motor I39 has positioned its operating shaft I40 so as to close the mercury switch I45, while allowing the mercury switches I46, I41, and I48 to remain open. At this time, all of the compressors, the various pumps, and the cooling tower fans are out of operation. Now if the switch I3 is closed for placing the pump motor I2 of the cold water circulating pump into operation, the mercury switch 2| of the pressure responsive device I1 will be tilted to closed position due to the resulting increase in pressure at the pump discharge. Closure of the mercury switch 2| will complete a circuit for energizing the relay coil 92 of the starting box 9| for the cooling tower pump 88. This circuit is as follows: line wire I50, wire I5 I, mercury switch 2|, wire I52, wire I53, wire I54, mercury switch I45, wire I55, and coil 92 to ground. It will be noted that the other line wire I56 is grounded. The resulting energization of the coil 92 will cause the switch arms 93 to engage their respective ccntacts for completing the power circuit to the pump motor 90 thus placing the pump 88 into operation. When the pump 88 is Placed into operation, the mercury switch II8 of the pressure responsive device 5 will close, thereby completing a circuit to the starting box of the cooling tower fan 18 as follows: line wire I50, wire I5I, mercury switch 2|, wire I 52, wire I53, wire I51, wire I58, mercury switch H8, wire I59, and starting box- 80 to ground. This will place the cooling tower fan 18 into operation and this action will cause closing of 5 the sail switch I28 will complete a circuit to the starting box 63 of the compressor 54 as follows: line wire I50, wire I5I, mercury switch 2I, wire I52, wire I60, sail switch I28, wire I6I, and starting box 63 to ground. This will place the compressor 55 in operation therebycausing chilling of the water passing through the water cooler II.

From the foregoing it will be seen that before the compressor 55 is placed into operation, the cold water pump 8 must be running, the cooling l5 tower pump 88 for the condenser must be run ning, and'in addition the cooling tower fan 18 must be, in operation. The control system described thus far therefore acts to prevent operation of the compressor unless the remainder of 20 the system is operating satisfactorily, thereby avoiding any danger of damage to the system due to failure of proper condensing withinthe condenser-receiver and also preventing any danger of freezing the water in the water cooler.

Also, it should be noted that due to the sequential control arrangement wherein the cooling tower pump is not started until after the cold water pump 8 is in operation, and in which the cooling tower fan is not started until the pump 88 operates, and in which the compressor 55v is not started until after the cooling tower fan is started, any chance of overloading the power lines to the system due to simultaneous starting of the motors is avoided. The control system thus far described therefore has the function of preventing the compressor 55 from operating unless the remainder of the system is operating properly, and has the further function of starting the various motors in sequence for preventing any possibility of overloading the power lines.

' If the cooling load upon the system increases due for instance to hotter air being passed over.

cooling coils 6 and 28, the temperature of the waterv leaving the water cooler will gradually in- 5 crease. This action will cause the slider I36 .of the thermostat I 30 to shift to the left across resistance I36 thus causing further counterclockwise rotation of the shaft I40, this causing the cam I42 to tilt mercury switch I46 to closed 50 position. Closure of mercury switch I46 will complete an energizing circuit to the starting box 64 of the compressor 56 as follows: wire I6I, wire.'I62, mercury switch I46, wire I63 and starting box 64 to ground. This will place the compressor 56 into operation for increasing the amount of cooling performed upon the water within the water cooler ,I I. Upon still further increase in load upon the system the temperature of the cold water leaving the water cooler II will increase, which will cause additional rotation of the shaft I40 in a clockwise direction thus tilting the mercury switch I41 to closed position. mercury switch I41 will establish an energizing o5 circuit for the relay I04 which controls the valve I 02 at the inlet of the cooling tower 13. This circuit is as follows: from line wire I50, wire I.5I, mercury switch 2I, wire I52, wire I53, wire I64, mercury switch I41, wire I65 and relay coil I05 to ground. This will cause the switch arm I06 of relay I04 to engage the contact I01 for causing the valve motor I03 to open valve I02 and to close the mercury switch IIO of auxiliary switch I09. The closure of the mercury switch IIO will complete a circuit to the starting box 95 for the Closure of -the pump motor 94 as follows: Line wire I50, wire I5I, mercury switch 2|, wire I52, wire I53, wire I51, wire I66, wire I61, wire I68, mercury switch IIO, wire I69 and starting box 95 to ground. This will place cooling tower pump 89 into operation. It should be noted at this time that the first action resulting from closing of the mercury switch I41 is the opening of valve I02 for permitting cooling water to flow to the spray pipe 15 of the cooling tower 13. When this valve is opened the pump 89 is placed into operation for pumping water from the condenser receiver to the spray pipe 15. Thus it should be noted that when only the cooling tower pump 88 is in operation, the valve I02 is closed thus causing all of the water delivered by pump 88 to be discharged to the cooling tower 12. When the mercury switch I41 closes, however, the valve I02 is opened and the pump 89 is placed into operation for delivering water to the spray pipe 15 of cooling tower 13. By this arrangement the pressure at the spray pipe 14 is not affected when the spray pipe 15 is placed into operation, as the pump 89 will supply an additional quantity of water thereby providing an adequate supply of water for both spray pipes.

When the pump 89 is placed intooperation the pressure responsive device I20 will close its mercury switch I23 which will complete an energizing circuit for the starting box 83 of the cooling tower fan motor 82 as follows: from wire I 66, wire I10, mercury switch I23, wire I1 I and starting box 83 to ground; This will place the cooling tower fan 8I into operation and in response to this action the mercury switch I21 of the sail switch I25 will close. l, Closure of the mercury switch I25 will establish an energizing circuit for the starting box 65 for compressor motor 6| as follows: wire I61,- wire I12, mercury switch I25,

wire I13, wire I14 and starting box 65 to ground. This will place the compressor 51 into operation for increasing the amount of refrigeration-performed by the system. It should be noted that before the compressor 51 is placed into operation the valve I02 must be open, the pump 89 must be in operation, and the cooling tower fan 8I must be in operation.- The additional load imposed upon the condenser-receiver by operation of the compressor 51 therefore cannot be placed upon this condenser-receiver unless the cooling tower 13 is operating properly. Also due to the sequential control arrangement by which operation of one device is dependent upon operation of another, the pump motor 94, the fan motor 82, and the compressor motor 6'I will be started in sequence thereby avoiding excessive loading of the power lines as would occur if these motors were started simultaneously. It should also be noted that the energizing circuit for the starting boxes 95, 83, and 65, is through the mercury switch 2I of the controller I 1. Consequently when the pump 8 is out of operation neither the pump 89, the fan 8I, nor the compressor 51 will operate.

This prevents any possibility of freezing the water in the water cooler II.

If the load upon the system increases still further the slider I35 of the thermostat I30 will cause further clockwise rotation of the shaft I40 for closing the mercury switch I48. This will establish an energizing circuit for the starting box 66 of compressor motor 62'a's follows: wire I13, wire I15, mercury switch I48, wire I 16, and starting box 66 to ground. This will place the compressor 58 into operation for further increasing the amount of refrigeration performed. Upon tor a refrigeration system having heat exchange diminishing of the cooling load upon the system it.will be apparent that the various compressors, pumps, and fans will be placed out of operation in inverse order.

From the foregoing it should be apparent that I have provided a flexible control system for controlling the various compressors, pumps, and fans of a large refrigeration system and provide for varying the number of compressors in operation in accordance with the load upon the system. It should also be noted 'that my improved control system automatically uses but one cooling tower when only a part of the compressors are in operation and automatically places the second cooling tower into operation when a predetermined num ber of compressors are required to be placed in operation. It should be further noted that my improved control system provides for automatically checking the operation of the cold water pump, the cooling'tower pump, and the cooling tower fan and prevents operation of a compressor in the event that one of these devices is not operating properly. It should additionally be notedthat my control system provides for not only checking the operation of these devices but sequentially places the various motors into opera tion for preventing large surges in current due to simultaneous starting of a plurality of motors of large size.

Also from the foregoing description it should be apparent that my invention provides for the utilization of a plurality of cooling towers and for varying the number of cooling towers in operation in accordance with the load on the system, while at the same time utilizing but a single pipe leading from the condenser to the cooling towers. My invention therefore avoids the necessity of running separate pipes from the condenser to each coolingtower and thus provides for materially reducing the cost of a large installation.

While I have shown and described -a preferred embodiment of my invention, it will be apparent that many modifications of the various instrumentalities which are within the scope of my invention will occur to those skilled in the art. I therefore desire to be limited only by the scope of the appended claims.

I claim as my invention:

1. In a system of the class described, in combination, heat exchange means, a first heat exchanger, a second heat exchanger, means including common conduit means for conveying heat exchange medium between each of said heat exchangers and said heat exchange means, pumping means for causing said heat exchange medium to flow through said conduit means, a controller for varying the operation of said pumping means, valve means for interrupting the flow of heat exchange medium between one only of said heat exchangers and said heat exchange means, motor means for opening and closing said valve means, and switching means actuated directly by said motor means for actuating said controller in a manner to increase the operation of said pumping means when the valve is opened and to decrease the operation of said pumping means when the valve is closed.

2. In a system for supplying cooling medium means requiring cooling medium, in combination, a first cooling device for cooling the cooling medium, a second cooling device for cooling the cooling medium, means including common conduit means for conveying cooling medium between said cooling devices and said heat exchange means, pumping means for causing said cooling medium to flow through said conduit means, control means for varying the output of said pumping means, valve means for interrupting the flow of cooling medium between one only of said cooling devices and said heat exchange device, motor means for opening and closing said valve means, and means for controlling said controller and said Valve motor means in a manner to open said valve means and to increase the operation of said pumping means, or to close said valve means andldecrease the operation of said pumping means. I

3. In a system for supplying cooling medium for a refrigeration system having heat exchange means requiring cooling medium, in combination, cooling tower means including a first spray device and a second spray device, means for conveying cooled cooling medium from said cooling tower means to said heat exchange means, means including a common conduit for conveying heated cooling medium from said heat exchange means to thespray devices, pumping means for forcing said cooling medium through said common-conduit to said spray devices, control means for varying the output of said pumping means, valve means for interrupting the flow to one only of said spray devices, motor means for opening and closing said valve means, and remote control means for controlling said valve motor means.

4. In a system for supplying cooling medium for a refrigeration system having heat exchange means requiring cooling medium, in combination, cooling tower means including a first spray device and a second spray device, means for conveying cooled cooling medium from said cooling tower means to said heat exchange means, means including a common conduit for conveying heated cooling medium from said heat exchange means to-the spray devices, pumping means for forcing said cooling medium through said common conduit to said spray devices, a controller for varying the output of said pumping means, valve means for interrupting the flow to one only of said spray devices, motor means for opening and closing said valve means, and means for actuating said controller and said valve motor means for thereby placing one of said spray devices into or out of operation without varying the pressure of the medium supplied to the other spray device.

5. In a system for supplying cooling medium for a refrigeration system having heat exchange means requiring cooling medium, in combination, cooling tower means including a first spray device and a second spray device, means for conveying cooled cooling medium from said cooling tower means to said heat exchange means, means including a common conduit for conveying heated cooling medium from said heat exchange means to the spray devices, pumping means for forcing said cooling medium through said common conduit to said spray devices, a controller for varying the output of said pumping means, valve means for interrupting the flow to one only of said spray devices, motor means for opening and closing said valve means, and means actuated by said motor means for actuating said controller in a manner to increase the operation of said pumping means when the valve is opened, and to decrease the operation of said pumping means when means requiring cooling medium, in combination, cooling tower means including a first spray device and a second spray device, means for conveying cooled cooling medium from said cooling tower means to said heat exchange means, means including a common conduit for conveying heated cooling medium from said heat exchange means to the spray devices, pumping means for forcing said cooling medium through said common conduit to said spray devices, a controller for varying the output of said pumping means, valve means for interrupting the fiow to one only of said spray devices, valve motor means for opening and closing said valve means, fan means for said cooling tower means, a fan controller for varying the operation of said fan means, a controller for said valve motor means, means actuated by said valve motor means for actuating said pumping means controller, and means actuated by the pressure produced by said pump ing means for controlling said fan means.

7. In a system for supplying coolingmedium for a refrigeration system having heat exchange means requiring cooling medium, in combination, cooling tower means including a first spray device and a second spray device, means for conveying cooled cooling medium from said cooling tower means to said heat exchange means, means including a common conduit for conveying heated cooling medium from said heat exchange means to the spray devices, pumping means for forcing said cooling medium through said common conduit to said spray devices, a controller for varying the output of said pumping means, valve means for interrupting the flow' to one only of said spray devices, valve motor means for opening and closing said valve means, fan means for said cooling tower means, a fan controller for varying the operation of said fan means, a controller for said valve motor means, means actuated by said valve motor means for actuating said pumping means controller, means actuated by the pressure produced by said pumping means for controlling said fan means, and means actuated by operation of said fan means for controlling the operation. of said refrigeration system.

8. In a refrigeration system, in combination, a compressor, a condenser, a cooling tower for supplying cooling water for said condenser, a fan for said cooling tower, a conduit for conveying water from said condenser to said cooling tower, pumping means, valve means for controlling the fiow of water between said condenser and cooling tower, motor means for actuating said valve means, control means responsive to the position of said valve means, control means responsive to operation of said fan means, control means responsive to operation of said pumping means, and means controlled by each of said control means for preventing operation of said compressor unless said valve is open, the pumping means is in operation, and the fan is in operation.

9. In a refrigeration system, in combination, a compressor, acondenser, a cooling tower for supplying cooling water for said condenser, a fan for said cooling tower, conduit means for conveying water between said cooling tower and 'condenser, pumping means for causing cooling water to fiow through said conduit means, a controller for said fan means, said pumping means, and said compressor, control means responsive to operation of said fan means, control means responsive to operation of said pumping means, and means controlled by said control means for preventing operation of said compressor unless fan means and compressor, control means re-' sponsive to operation of said fan means, and means controlled by said control means for preventing operation of said compressor unless the fan means is in operation.

11. In a refrigeration system, in combination, a pair of compressors, condensing means, means for supplying cooling medium to said condensing means including a first pump and a second pump, a condition responsive means responsive to a condition which is a measure of the load on the system for sequentially placing said compressors and pumps in operation as the load upon the system increases, control means responsive to operation of one of said pumps, means controlled by said control means for preventing operation of one of said compressors when said one pump is not in operation, control means responsive to operation of said other pump, and means controlled by said last mentioned control means for preventing operation of said other compressor when said other pump is not in operation.

12. In a refrigeration system, in combination, a pair of compressors, condensing means, means for supplying cooling medium to said condensing means including cooling tower means having a first spray device and a second spray device, a first fan means for said first spray device; a second fan means for said second spray device, first and second pumping means for forcing cooling medium to said spray devices, control means including a condition responsive device responsive to a condition which is a measure of the load on the system for sequentially controlling said compres'sors, fan means, and pumping means, said control means being arranged for first placing one of said compressors, said first fan means and said first pumping means into operation and then placing said other compressor, said second fan means, and said second pumping means into operation as the load upon the system increases.

13. In a refrigerating, system, in combination, a pair of compressors, condensing means, means for supplying cooling medium to said condensing means including cooling tower means having a first spray device and a second spray device, a first fan means for said first spray device, a second fan means for said second spray device, first and second pumping means for forcing cooling medium to said spray devices, means including a condition responsive device responsive to a condition which is a measure of the load on the system for sequentially controlling said compressors, fan means, and pumping means, control means responsive to operation of said first fan means and said first pumping means, means controlled by said control means for preventing operation of one of said compressors when either said first fan means or said first pumping means isnot in operation, control means responsive to operation of said second fan means and said second pumping means, and means controlled by said last mentioned control means for preventing operation of said other compressor when either said second fan means or said second pumping means is not in operation.

14. In a refrigeration system, in combination, a pair of compressors, condensing means, means for supplying cooling medium to said condensing means including cooling tower means having a first spray device and a second spray device, common conduit means for conveying cooling medium from said condensing means to said spray devices, pumping means for causing said cooling medium to flow through said conduit means, a controller for varying the operation of said pumping means,

valve means for interrupting the flow of cooling.

medium to one only of said'spray devices, control means including a condition responsive device for sequentially controlling said compressors, said valve means and said pumping means, in a manner to place one of said compressors in operation, and then to place said other compressor into operation while opening said valve means and increasing the operation of said pumping means as the load upon the system increases.

15. In a refrigeration system, in combination, a pair of compressors, condensing means, means for supplying cooling medium to said condensing means including cooling tower means having a first spray device and a second spray device, common conduit means for conveying cooling medium from said condensing means to said spray devices, pumping means for causing said cooling medium to now through said conduit means, a controller for varying the operation of said pumping means, valve means for interrupting the flow of cooling medium to one only of said spray devices, means for controlling said compressors, control means responsive to the position of said valve means, control means responsive to increase in operation of said pumping means, and means controlled by both of said control means for preventing operation oi one of said compressors when either the valve is not in open position or the operation of said pumping means is not increased.

16. In a refrigeration system, in combination, a

first compressor, a second compressor, evaporator means, condensing means, power actuated means for causing heat exchangemedium to flow into heat exchange relationship with said evaporator meanspumping means for supplying cooling medium'to said condensing means, means including a condition responsive device responsive to a condition which is a measure of the load on the system for sequentially controlling said compressors and varying the operation of said pumping means in a manner to place one of said compressors into operation and then to place the other compressor into operation and increase the operation of said pumping means as the load on the system in creases, control means responsive to increase in operation of said pumping means, means controlled by said control means for preventing operation of said other compressor when the operation of said pumping means is not increased, control means responsive to operation of said power actuated means, and means controlled by said last mentioned control means for preventing operation of both of said compressors when said power actuated means is not in operation.

17. In a refrigeration system, in combination, compressing means, evaporator means, condensing means, pumping means for causing heat exchange medium to flow into heat exchange relationship with said refrigeration system, means including a condition responsive device responsive to a condition which is a measure of the load on the system for controlling the compressing means and the pumping means in a manner to increase the operation of said compressing means and said pumping means as the load upon the system increases, control means responsive to increase in operation of said pumping means, and means controlled by said control means for preventing increase in operation of said compressing means when the operation of said pumping means is not increased.

JOSEH E. ROBE. 

